Technical Field
The present invention relates to a capacitance-type touch sensor which detects a change in capacitance caused by proximity of a finger and other objects to the touch sensor.
Background Art
Touch sensors have been conventionally diffused widely as an input means for various signals. Among various types of touch sensors, a capacitance-type touch sensor which detects a change in capacitance caused by proximity of a finger to the touch sensor has been becoming mainstream.
Here, in a touch switch in which a touch sensor is employed, it is most common to form detection patterns on a circuit board. The space on the circuit board is suitable for fabrication of IC and other peripheral components, and forming detection patterns on the same circuit board promotes integration and ease of handling.
In such a touch sensor, a circuit board is disposed immediately under a casing (which will be referred to as a cabinet), and a change in capacitance in the detection patterns caused by touch of switch patterns designed on the cabinet with a finger is detected.
As this capacitance-type touch sensor, in addition to touch sensors in which direct-current voltage is applied to the capacitance, alternating current type touch sensors have been also proposed (JP 2010-182290). These alternating-current type touch sensors are advantageous over the direct-current type because of higher sensitivity.